This invention relates to a fastener driving tool, and in particular one comprising an adapter means for use in combination with a power torque wrench to rapidly rotate a socket member of the torque wrench prior to final torquing.
Various power torque wrenches are known in the art in which a ratchet mechanism rotates an output shaft and a socket coupled thereto about a central axis to loosen or tighten threaded fasteners. In some wrench designs, such as that described in U.S. Pat. No. 4,506,567 to Makhlouf, an internal gear and chain drive effects the rotation of the ratchet mechanism. In other designs, such as in those intended to deliver high torquing forces, the ratchet pawl is driven by a reciprocating fluid actuated piston, thereby converting linear force into angular force.
A variety of means have also been proposed for coupling the article engaging socket to the ratchet mechanism of a torque wrench. U.S. Pat. No. 4,838,130 to Snyder, for example, describes a power torque wrench which combines the features of a ratchet gear and article engaging socket in a single component. The '130 device utilizes an annular disc member having an interior opening corresponding to the size of the fastener to be turned and an outer peripheral edge having a plurality of flat surfaces. Each adjacent pair of flat surfaces forms a point with the direction of the points alternating between the interior and exterior of the disk member. A piston driven pawl engages against a flat section of the disk member to thereby rotate a threaded member retained within the interior opening. U.S. Pat. No. 2,961,904 to Sergan utilizes a central member also driven by hydraulic cylinders to rotate a threaded fastener or an auxiliary tool carrying an appropriately shaped fastener engaging element.
In U.S. Pat. No. 4,137,800 to Austin, it is proposed that a ratchet mechanism of a torque wrench include a tubular shaft provided with a splined outer peripheral surface portion to define a plurality of teeth which are engaged by a pawl for rotation. The interior surface of the shaft defines a plurality of longitudinally extending female splines. A single socket receiving adapter has a socket engaging extension on one end and splines on the opposite end which are dimensioned so as to be received within the female splines of the output shaft. The adaptor may be removed from one side of the shaft and replaced on the other side so that bolts may be loosened or tightened as desired. Other torque wrenches utilizing output shafts having female splines for receiving correspondingly splined socket adapters are described in U.S. Pat. Nos. 4,706,527 and 5,056,384.
Each of the torque wrenches discussed above are capable of applying relatively high torquing forces (at varying levels of precision). However, one drawback associated with such systems is that they are inefficient in applications where many turns of the threaded fasteners are necessary before any high tightening force is required. Specifically, the relatively short travel of the fluid actuated pistons limits rotation of the output shaft and socket attached thereto to relatively small increments. As a result, use of such prior art power torque wrenches to tighten fasteners from a loosened condition to a position for final torquing requires many actuations and can be very time consuming.
U.S. Pat. No. 4,137,800 attempts to avoid the failings of the other prior art devices by incorporating a provision enabling the user to detachably connect an extension handle whereby a torque output may be manually applied to the output shaft. A torque arm coupled to the output shaft is rotated by engagement with a reciprocating block connected to the piston. To pretighten a threaded fastener, the user of the '800 wrench inserts the extension handle into a cavity of the torque arm and rotates it manually, thereby overriding the hydraulic actuator section of the wrench.
While the patented wrench disclosed in the '800 patent is an improvement over previously available wrenches in that it expedites pretightening of threaded fasteners, its design is still not satisfactory for all situations. The manually operated handle can only be rotated approximately 180.degree. at a time and does not allow for use with a power tool such as an air wrench. This device thus also requires the user to expend extra time and energy where many untightened fasteners are involved. The operating speed is a very important criteria in torque wrenches as described herein, especially if the wrench is to be successfully utilized in limited manpower situations.